TypeError in read_vector_history_from_file (TUDAT): Eigen::Matrix Conversion Issue

[luigigisolfi]

Question

User:
Hi people!
I was trying to use the function read_vector_history_from_file from the io module in tudat, but received the following error:
TypeError: Unregistered type : Eigen::Matrix<double,-1,1,0,-1,1>

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Program Files\JetBrains\PyCharm 2021.2.1\plugins\python\helpers\pydev\pydevd.py", line 1483, in _exec
    pydev_imports.execfile(file, globals, locals)  # execute the script
  File "C:\Program Files\JetBrains\PyCharm 2021.2.1\plugins\python\helpers\pydev\_pydev_imps\_pydev_execfile.py", line 18, in execfile
    exec(compile(contents+"\n", file, 'exec'), glob, loc)
  File "C:/Users/viero/PycharmProjects/ThesisProject/Just_aerocapture/just_aerocapture_numerial_uncertaintyPropagation_plots.py", line 294, in <module>
    heat_fluxes_history = read_vector_history_from_file(2, data_path + 'heat_fluxes_history_' + str(run_number) + '.dat')
TypeError: Unable to convert function return value to a Python type! The signature was
	(vector_size: int, file_name: str) -> Dict[float, Eigen::Matrix<double,-1,1,0,-1,1>]

I followed the instructions in the documentation of the function, so I guess it might be some error in the c++ code or something related. Anybody knows what might be the cause of this behaviour?
The way i used it is:

heat_fluxes_history = read_vector_history_from_file(2, data_path + 'heat_fluxes_history_' + str(run_number) + '.dat')
And the file has a structure like:
975715200.0    0.0    0.0
975755200.0    0.0    0.0
975915200.0    0.0    0.0
976347200.0    0.0    0.0
...

[luigigisolfi]

Answer

Tudat-team:
Hi, this error has been a deeply confusing thing that I haven't yet found a good solution to.....
For some reason, on some Python versions (?) compilers (?) pybind can't seem to convert std::map containers with Eigen types in them, if this map is the return type of a free function. If you can open an issue on this https://github.com/tudat-team/tudat, we can be reminded to fix this. Are you using the conda package or a manually compiled kernel?
The short-term solution is to add an additional function in C++ that returns a pair of vectors instead of a map (with the vectors containing the keys and values). For some reason pybind seems to be fine with this...

[luigigisolfi]

User:
I can easily find a workaround, that's not a big issue. I was more curious of what the cause of the error was, but sure, I'll open an issue on github!
Anyway, I'm using a conda package yes. I mean I use anaconda to manage the tudat environment i use.

[larshinueber]

For future reference, this has been resolved with tudatpy v0.9.0 :)